HE on a Baxi heat pump: Condenser refrigerant outlet temperature too high in heating mode for more than 10 minutes
Short answer
On a Baxi heat pump, HE means: Condenser refrigerant outlet temperature too high in heating mode for more than 10 minutes. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the Assure Monobloc ASHP (Assure Mono 5/7/9/12/16)
The manual says: Condenser refrigerant outlet temperature too high in heating mode for more than 10 minutes.
Part involved: refrigerant pressure / temperature.
Likely causes:
- If outside temperature is above 30°C the unit will not operate in heat mode.
On the HP40 / Baxi Assure HP50 Monobloc ASHP
The manual says: Communication error between main board and thermostat transfer board.
Part involved: PCB communication wiring.
Likely causes:
- RT/Ta PCB set valid on user interface but thermostat transfer board not connected or not communicating; set RT/Ta PCB invalid if not needed, otherwise check board connection and wiring/interference.
Is it safe?
On the Assure Monobloc ASHP (Assure Mono 5/7/9/12/16)
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: Power OFF/ON after correcting cause (ISM 13.4).
On the HP40 / Baxi Assure HP50 Monobloc ASHP
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: Installer: correct cause then power OFF/ON (ISM 13.4).
What you can check
On the Assure Monobloc ASHP (Assure Mono 5/7/9/12/16)
- Note the exact code shown on the controller and when it appeared.
- Check the outdoor unit is not blocked by leaves, debris, snow or covers and has clear airflow.
- If the code persists or returns, contact a heat pump engineer.
On the HP40 / Baxi Assure HP50 Monobloc ASHP
- Note the exact code shown on the controller and when it appeared.
- If the code persists or returns, contact a heat pump engineer.
What the engineer will check
On the Assure Monobloc ASHP (Assure Mono 5/7/9/12/16)
- If outside temperature is above 30°C the unit will not operate in heat mode.
Who to ask for: heat pump / refrigeration engineer (F-gas).
Certification: F-gas certification (Category I) for refrigerant work.
On the HP40 / Baxi Assure HP50 Monobloc ASHP
- RT/Ta PCB set valid on user interface but thermostat transfer board not connected or not communicating; set RT/Ta PCB invalid if not needed, otherwise check board connection and wiring/interference.
Who to ask for: heat pump engineer (controls / sensors).
Certification: Manufacturer-trained heat pump engineer.
What you might notice
Sources
- Installation and owner's manual - Heat Pump air/water 'inverter' Assure Mono 5, 7, 9, 12, 16 ↗ · Back cover shows '7762758 - v05 - 19082020' (same number as the Assure Split manual - probably shared back-cover artwork) · page 74 · Reviewed 23 September 2026
- Installation and Service Manual - Heat Pump air/water 'inverter' HP40/50-4-1PHMB to HP40/50-13-3PHMB (United Kingdom) ↗ · 784570-01 (v1) · page 74 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026